\begin{tikzpicture}
    \tkzDefPoints{0/0/C, 4/0/B, 4/3/A}
    \tkzDrawSegments(A,C)
    \tkzDrawSegments[dashed](A,B)
    \tkzDrawLine[add=0 and 0.2](C,B)
    \tkzMarkRightAngle[size=0.2](A,B,C)
    \tkzLabelPoints[above](A)
    \tkzLabelPoints[below](B)
    \tkzLabelPoints[left](C)

    %
    \tkzDefPointOnLine[pos=0.5](A,B)  \tkzGetPoint{O}
    \tkzDrawEllipse[
        pattern={mylines[angle=65, distance={4pt}]},
        decorate, decoration={random steps,segment length=3pt,amplitude=1pt}
    ](O,0.5,1.2,0)
\end{tikzpicture}

